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Vikinghøgda Formation
The Vikinghøgda Formation is a geologic formation in Svalbard, Norway. It preserves fossils dating back to the Early Triassic (Griesbachian-Spathian) period. It is split into three members, from oldest to youngest: the Deltadalen Member (Induan), Lusitaniadalen Member ( Smithian), and Vendomdalen Member (Spathian). The formation can be found in central and southern Spitsbergen, as well as the smaller islands of Barentsøya and Edgeøya. The type locality is positioned in the vicinity of Vikinghøgda and Sticky Keep, two low peaks along the southeast edge of the Sassendalen valley in Spitsbergen. The two upper members of the Vikinghøgda Formation were previously grouped together as the Sticky Keep Formation. Subunits The Vikinghøgda Formation is formed by fine-grained marine sediments, such as mudstones, shales, siltstones, and fine sandstones. There is a trend of finer sediments, deeper waters, and higher organic content through the formation. Though fossils are only abunda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossilworks
Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ..., a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was created in 1998 by John Alroy and is housed at Macquarie University. It includes many analysis and data visualization tools formerly included in the Paleobiology Database.{{cite web, title=Frequently asked questions, url=http://www.fossilworks.org/cgi-bin/bridge.pl?page=FAQ, publisher=Fossilworks, access-date=17 December 2021 References {{Reflist External links {{Wikidata property, P842 * [Baidu] |
Hummocky Cross-stratification
Hummocky cross-stratification is a type of sedimentary structure found in sandstones. It is a form of cross-bedding usually formed by the action of large storms, such as hurricanes. It takes the form of a series of "smile"-like shapes, crosscutting each other. It is only formed at a depth of water below fair-weather wave base and above storm-weather wave base. They are not related to "hummocks" except in shape. History The name was introduced by Harms et al. in 1975. Before this time, these structures were recognized under many different names. When hummocky cross-stratification was founded, it was originally given the name “truncated wave-ripple laminae,” by Campbell (1966, 1971).Surlyk, F., and N. Noenygaard. "Hummocky Cross-stratification from the Lower Jurassic Hasle Formation of Bornholm, Denmark." ''Sedimentary Geology'' 46.3-4 (1986): 259-73. Print. The main features were listed by Bourgeois (1980), Harms et al. (1982), and Walker (1983), in order to identify the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glauconitic Sandstone
Greensand or green sand is a sand or sandstone which has a greenish color. This term is specifically applied to shallow marine sediment that contains noticeable quantities of rounded greenish grains. These grains are called ''glauconies'' and consist of a mixture of mixed-layer clay minerals, such as smectite and glauconite. Greensand is also loosely applied to any glauconitic sediment. Formation Greensand forms in anoxic marine environments that are rich in organic detritus and low in sedimentary input. Having accumulated in marine environments, greensands can be fossil-rich, such as in the late-Cretaceous deposits of New Jersey. Occurrence Important exposures are known from both northern and western Europe, North America, southeastern Brazil and north Africa. Well known and important greensands are the Upper and Lower Greensands of England and occur within Eocene and Cretaceous sedimentary strata underlying the coastal plains of New Jersey and Delaware. Although greensand has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclostratigraphy
Cyclostratigraphy is a subdiscipline of stratigraphy that studies astronomically forced climate cycles within sedimentary successions. Orbital changes Astronomical cycles (also known as Milankovitch cycles) are variations of the Earth's orbit around the sun due to the gravitational interaction with other masses within the solar system. Due to this cyclicity, solar irradiation differs through time on different hemispheres and seasonality is affected. These insolation variations have influence on Earth's climate and on the deposition of sedimentary rocks. The main orbital cycles are precession with main periods of 19 and 23 kyr, obliquity with main periods of 41 kyr, and 1.2 Myr, and eccentricity with main periods of around 100 kyr, 405 kyr, and 2.4 Myr. Precession influences how much insolation each hemisphere receives. Obliquity controls the intensity of the seasons. Eccentricity influences how much insolation the Earth receives altogether. Varied insolation directly influe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetostratigraphy
Magnetostratigraphy is a geophysical correlation technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout the section. The samples are analyzed to determine their ''characteristic remanent magnetization'' (ChRM), that is, the polarity of Earth's magnetic field at the time a stratum was deposited. This is possible because volcanic flows acquire a thermoremanent magnetization and sediments acquire a depositional remanent magnetization, both of which reflect the direction of the Earth's field at the time of formation. This technique is typically used to date sequences that generally lack fossils or interbedded igneous rock. Technique When measurable magnetic properties of rocks vary stratigraphically they may be the basis for related but different kinds of stratigraphic units known collectively as ''magnetostratigraphic units (magnetozones)''. The magnetic property most useful in stratigraphic work is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palynomorph
Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and '' -logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposits including sediments of any age. The condition and identification of those particles, organic and inorganic, give the palynologist clues to the life, environment, and energetic conditions that produced them. The term is commonly used to refer to a subset of the discipline, which is defined as "the study of microscopic objects of macromolecular organic composition (i.e., compounds of carbon, hydrogen, nitrogen and oxygen), not capable of dissolution in hydrochloric or hydrofluoric acids". It is the science that studies contemporary and fossil palynomorphs (paleopalynology), including pollen, spores, orbicules, dinocysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronostratigraphy
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth. The standard stratigraphic nomenclature is a chronostratigraphic system based on palaeontological intervals of time defined by recognised fossil assemblages (biostratigraphy). The aim of chronostratigraphy is to give a meaningful age date to these fossil assemblage intervals and interfaces. Methodology Chronostratigraphy relies heavily upon isotope geology and geochronology to derive hard dating of known and well defined rock units which contain the specific fossil assemblages defined by the stratigraphic system. In practice, as it is very difficult to isotopically date most fossils and sedimentary rocks directly, inferences must be made in order to arrive at an age d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Index Fossils
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. The primary objective of biostratigraphy is ''correlation'', demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to help identify biozones, as they make up the basic biostratigrap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sassendalen
Sassendalen is a valley at Spitsbergen, Svalbard. The valley is among the largest valleys of Svalbard, and continues westwards into Sassenfjorden. Part of the valley divides Sabine Land and Nordenskiöld Land Nordenskiöld Land is the land area between Isfjorden and Van Mijenfjorden on Spitsbergen, Svalbard. The area is named after Finnish-Swedish explorer and geologist Nils Adolf Erik Nordenskiöld. The coastal region of Nordenskiöld Land (Norde ... . The river Sassenelva runs through the valley. References Valleys of Spitsbergen {{Spitsbergen-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edgeøya
Edgeøya (), occasionally anglicised as Edge Island, is a Norwegian island located in southeast of the Svalbard archipelago; with an area of , it is the third-largest island in this archipelago. An Arctic island, it forms part of the Søraust-Svalbard Nature Reserve, home to polar bears and reindeer. An ice field covers its eastern side. The island takes its name from Thomas Edge (died 1624), an English merchant and whaler. It is seldom visited today and development of tourist facilities is forbidden by law because of its nature reserve status. History The history of Edgeøya's discovery has been a matter of dispute. Thomas Edge, writing in 1622, claimed the island was discovered by one of his ships in 1616. However, Joris Carolus, in a map published in 1614 and allegedly based on discoveries made by him the same year, shows what appears to be Edgeøya's south coast. Carolus showed the coastline split into two parts: "Onbekende Cust" (meaning "Unknown Coast" in Dutch) in the wes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barentsøya
Barentsøya, sometimes anglicized as Barents Island, is an island in the Svalbard archipelago of Norway, lying between Edgeøya and Spitsbergen. Barents Island has no permanent human inhabitants. Named for the Dutch explorer Willem Barents (who actually never sighted the island), it is a part of Søraust-Svalbard Nature Reserve. Barentsøya is an Arctic island. Around 43 per cent of its area of is glaciated. To the north, in the sound between Barentsøya and Spitsbergen, lies the island of Kükenthaløya. To the south, the sound separating Barents Island from Edgeøya is Freemansundet. In geologic time much of the surface rock has been eroded by glaciation. The entire area is visited by polar bears, who have a recognisable genetic differentiation specialised to the Barents Sea region. At Dørstubukta there is also a large nesting mainly used by kittiwakes. Geography Barentsøya has an approximately square shape, with maximum lengths and widths of about fifty kilometers, and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
